Lighting fixtures

ABSTRACT

An indirect lighting fixture comprising an injection moulded tubular nontranslucent member having an internal light source at one end and screw threads formed about the interior thereof to reflect light from the source from the insides of the member and towards the light surface, the screw threads being formed during injection moulding of the member by a screw form core which is subsequently unscrewed from the member while the latter is held by the mould.

United States Patent 2,514,486 7/1950 Green 2,551,710 5/1951 Slaughter 240/108 (X) 2,773,172 12/1956 Pennou 240/106 (X) 3,253,276 5/1966 Nagel 240/106 (X) FOREIGN PATENTS 164,141 6/1954 Australia 240/106 1,181,145 11/1964 Germany 240/108 Primary Examiner- Samuel S. Matthews Assistant ExaminerRichard L. Moses Attorney-Watts, Hoffmann, Fisher and Heinke ABSTRACT: An indirect lighting fixture comprising an injection moulded tubular nontranslucent member having an internal light source at one end and screw threads formed about the interior thereof to reflect light from the source from the insides of the member and towards the light surface, the screw threads being formed during injection moulding of the member by a screw form core which is subsequently unscrewed from the member while the latter is held by the mould.

PATENTEU .1112 7 I911 MT Au-M BY M, 4

ATTORNEY INVENTOR mud-w LIGHTING FIXTURES The present invention relates to a lighting fixture of the type which comprises a tubular member which is adapted to be mounted with a light source adjacent one end and with the light beams extending through the tube to give an indirect lighting effect.

To this purpose the reflection of the light beams in the interior of the tubular member must be substantially suppressed so that a person who is located where he cannot see the light source has an undisturbed impression of indirect lighting.

it is well known in the art to obtain this optical effect by means of a plurality of interior annular projections in the tubular member.

It is the purpose of the invention to provide a novel construction of a lighting fixture of the kind hereinbefore referred to which lends itself to rational mass production technique and enables lightning fixtures of the kind referred to to be economically manufactured.

It is a further purpose of the invention to provide amethod of manufacturing a lighting fixture of the kind referred to which is adaptable to automation.

The invention will be further described in the following with reference to the accompanying drawing, in which FIG. 1 is a perspective view of lighting fixture according to the invention, and

FIG. 2 is a section through the lighting fixture.

The lighting fixture illustrated in the drawing is in the form of a tubular member which as illustrated in FIG. 2 is adapted to be mounted in a manner not shown with a lighting source 12 at one end for example, the tubular member could be mounted in a recess in a ceiling so that the end opposite the light source only is visible.

At the end where the lighting source 12 is provided, the tubular member has an interior surface portion l4-of general cylindrical configuration. The rest of the interior surface of the tubular member 10 is provided with a plurality of annular projections in the form. of screw heads 16 integral with the tubular member. As may be seen in FIG. 2 the screw threads are V-shape in cross section.

These annular projections are so dimensioned relatively to the height and diameter of the tubular member that the light beams whichare directed against the interior wall of the tubular member only will hit the surfaces of the screw threads which face the light source.

Thereby reflections in the interior of the tubular member are avoided and a person is located so that he cannot see the light source 12 will have the impression of indirect lighting without'any disturbing reflections.

As an example of the dimensions the pitch of the screw threads may be approximately 2 millimeters and their radial extension 0.07 millimeter in the case of a tubular member which has an interior diameter of approximately 13 /2 centimeters and which extends approximately 13 centimeters below' the light source.

ln comparison with construction of the annular projections by turning on a lathe or in the form of resilient ring members, the screw threads provide for rational mass production of the lighting fixture with a substantial reduction of labor costs.

The tubular member is preferably manufactured by injection moulding in a mould in the interior of which a screw threaded core is provided and after the moulding the screw ing the unscrewing of the interior core, the tubular member is as shown provide with exterior pro ections preferably in the form of elongated axially extending ribs 18 which extend 'along a part of the length of the tubular member.

The mould may be constructed slightly conical so as to provide a slip for the moulded structure and the automatic unscrewing of the interior core may be combined with a reciprocation of the interior core so as to partly withdraw the moulded structure from the mould before the unscrewing operation is started.

It will be understood that the invention is not limited to the embodiment shown and described with reference to the drawing. Though within the scope of the invention any type of screw threads can be used, vee-threads are especially preferred because they do not leave any inwardly facing surfaces which can give rise to reflection. I

The lighting fixture according to the invention may be manufactured of any suitable nontransparent materials, preferably ofsynthetic resin which can be injection moulded.

lclaim:

l. A lighting fixture in the form of a tubular opaque member having a light source at one end, characterized by the interior wall of said member having a screw thread formed about the inside surface thereof, said screw thread being V-shape in cross section whereby the side of said thread facing said light source is joined to the opposite side of the thread by an acute angle. 

1. A lighting fixture in the form of a tubular opaque member having a light source at one end, characterized by the interior wall of said member having a screw thread formed about the inside surface thereof, said screw thread being V-shape in cross section whereby the side of said thread facing said light source is joined to the opposite side of the thread by an acute angle. 